Apparatus for applying powdered metal briquets to curved metallic surfaces



Jan. 6, 1948. s. K. WELLMAN 2,434,237 A APPARATUS FOR APPLYING POWDERED METAL BRIQUETS TO CURVED METALLIC SURFACES Filed Sept. 155,l 1943 2 Sheets-Sheet 1 Ik 1m uw Ha iml'm v J IN VEN TOR. BYK u/llman C. 72u40 @C AHj/s Jan. 6, 1948. s. K. WELLMAN 2,434,237

' APPARATUS FOR APPLYING POWDE HE BRIQUETS TO CUR ALLIC FAG vFil 13, 1943 2 Sheets-Sheet 2 Patented Jan. 6, 1948 APPARATUS FOR APPLYING POWDERED METAL BRIQUETS TO CURVED METALLIC SURFACES Samuel K. Wellman, Cleveland Heights, Ohio, ass'gnor to The S. K. Wellman Company, Cleveland, Ohio, a corporation of Ohio Application September 13, 1943, Serial No. 502,226

Claims. 1 This invention relates to apparatus for applying powdered metal briquets to curved surfaces, and more especially for applying brake liners to brake drums for vehicles and the like.

One of the objects of the invention is the proi vision of a new and improved apparatus for applying brake liners to brake drums in such manner that the material ofV the liner becomes intimately bonded to the material of the drum.

A further object of the invention is the provision of a new and improved apparatus whereby a plurality of brake drums may have simultaneously bonded thereon brake liners formed from sintered powdered metal without distorting thel brake drum iiange,

A still further object of the invention is the provision of a new and improved apparatus for applying brake liners made from powdered metal to brake drums in an efficient, economical and expeditious manner, and with an apparatus that is simple in construction and that may be operated with a, minimum of cost and labor.

Other and further objects and advantages of 4the invention will appear from the following description, taken in connection with the accompanying drawings in which Fig. 1 is a vertical section of a heat treating furnace, showing the brazing apparatus in position therein;

Fig. 2 is a Vertical section of the brazing apparatus, on the line 2-2 of Fig. 3;

Fig. 3 is asection on the line 3-3 of Fig. 2;

Fig: 4 is a vertical section of a portion of an inverted brake drum, showing the brake liners secured to the drum ange, and with a temporary reinforcing member in position thereon; and

Fig. 5 is a view similar yto Fig. 4, but showing the temporary reinforcing member removed.

It is well known that brake drums become scored and worn in use, resulting in uneven braking and rapid wear of the brake lining. The art pact it into the desired shape (usually about eleven tons per square inch is used) will sinter together and unite to form a porous metallic article of considerable strength if heated to an elevated temperature below the meltingv point of the metal powder. This compressed and sintered powdered metal may be composed of a mixture of metallic and non-metallic ingredients, so that it is possible to control the physical properties of the same and obtain an excellent friction surface having kthe desired coeicient of friction and heat transferability. However, .it is rather diflicult to secure sintered powdered metal to a solid steel backing member or drum.

` of the steel after it has been carefully cleaned.

has generally used a pressed steel brake drum or a cast iron brake drum. or combinations of the two. Steel has the requisite strength but lacks wear resistance. Cast iron has the necessary wear resistance but lacks strength. Therefore, it is common to provide a steel drum with a wearing surface layer of cast iron.

The present invention proposes to substitute a layer4 of sintered powdered metal for the cast iron lining in a'pressed steelbrake drum, in order to obtain bet-ter heat dissipation and the desired coefficient of friction, as may be predetermined.

Metal powder. if subjected to pressure to com- If metal powder is pressed against the prepared surface of the brake drum with suicient pressure', and heated to a sintering temperature while under pressure, it will bond thereto.

The sequence of operations may, therefore, be described as follows: Y

1. Press metal powder under a pressure of 11 tons per square inch to obtain a compact or briquet, which, for convenience of description,'

will hereinafter be termed a briquet.

2. Clean the surface of the brake drum and metallize this surface in any suitable manner, as by electroplating the same.

3. Place the briquet on the clean surface and press it thereagain'st under pressure, say, around 250 pounds per square inch.

4. Heat the drum and briquet while under pressure to sintering temperature, which will vary for different materials but which will be somewhere around 1600 F. It is heated and pressed until the metal powder sinters together and bonds to the steel.

As an alternative, the metal powder briquet may be sintered prior to step 3, in which case the final lheating step merely serves to bond the already sintered briquet tothe steel drum.

The above sequence of operations constitutes the usual operating procedure in producing cerv tain types of bimetallic metal, and i`s a conventional method in securing any powdered metal to a steel backing. In the case of annular surfaces,

3 it is exceedingly diicult to keep the briquet pressed against the steel backing during the sintering and bonding operation, and the present invention is designed to accomplish this object.

For simplicity of disclosure the application f powdered metal briquets to brake drums has been selected to illustrate one embodiment of the invention, but it is understood that this is by way of example only. and that the inventionrcontemplates the application of powdered briquets to curved surfaces wherever necessary or desirable.

Referring now to the drawing, the reference character I0 designates, generally, a heat treating furnace within which is mounted the brazing apparatus I The heat treating furnace Il) may be of any desirable construction, that shown being substantially the same as that disclosed in my Patent No. 2,258,431, of October 7, 1941, and which comprises a base portion I2, an intermediate or furnace covered structure I3 having top and side wallsv of refractory material, as is usual in such constructions. The intermediate portion is provided with electrical heating elements I4, and an air sealed member I5 extends over the brazing apparatus II, with its side walls extending down into loose insulating material I 6. Means for applying vair pressure to the brazing apparatus is shown at I1.

Since the details of the heat treating furnace constitute no part of the present invention, it is not thought necessary to further illustrate or describe the same.

The brazing apparatus II, which is positioned within the furnace I0, comprises a plurality of separate superposed sections or units E8, I9, and 2|, only four being shown; but the apparatus may be contracted or extended by removing one or more of the sections or by adding additional sections, as occasion may require, or for accommodating various sizes of heat treating furnaces. This is considered an important feature of the invention.

These sections are preferably, though not necessarily, duplicates of each other, except for the .bottom or foundation member 2| which may be regarded as having its lower portion removed. Its upper portion may be substantially like the upper portion of the other sections. Each of these sections isprovided on its upper surface with an annular stepped portion conforming to the brake drum, as shown in Fig. 2. In other words, each section isV lcylindrical in form and has a lower horizontal portion 22, on which the attaching flange 23 of a brake drum 20a is adapted to rest and be. clamped in position by suitable bolts or screws.24 extending through the attaching flange 23 into the section. Each section is provided with a top horizontal portion 25 above, and offset radially outwardly from, the horizontal portion 22, on which an offset portion 26 of the brake drum 2|]a is adapted to seat. The brake drum fiange 21 extends vertically upwardly from the top of the section to which it is attached.

The lower portion of each section, except the lower or base section, is provided with means for positioning the brake liners or briquets on the brake flange, and for clamping the same in position during the heat treating operation. As shown, each of the upper sections is provided with a circular recess 28 extending upwardly from its bottom wall, and into which the drum flange 2I extends, as shown more clearly in Fig. 2 of the drawing. The recess 28 has upwardly Y converging walls 29 and 3|.

These walls are both shown as being inclined to the vertical and converge upwardly, but the wall opposite the briquet could, of course, be a vertical wall since it functions as an abutment wall reacting against the wedge on the opposite side of the brake flange. However, since the brazing apparatus is adapted to be used for creating opposite pressures against the brake drum flange, whether the briquet is secured to the inner or outer surface, it is preferred that both walls of the groove be inclined, as shown in Fig. 2.

With this arrangement the powdered metal briquets may be applied to either the inner or outer surface of the brake drum flange or to both sides, or some to one side of the drum flange and some to the other, simultaneously, as may be desired. By means of this arrangement pressure is applied to both sides of the brake flange, and consequently all danger of distorting the flange is eliminated.

The brakeliners 32, or rather what is destined Vto become the brake liners, are of powdered metal and conform to the surface of the brake drum flange r2'I, to which theyV are bonded. These liners are rst formed by applying pressure to powdered metal to form the same into the briquets 32B (Figs. 4 and 5), and these briquets are bent to conform to the curvature o the surface of the brake drum flange, whether they be applied to the inner or outer surface thereof.

Suitable means are provided for applying lateral pressure to the briquets and applying pressure for reinforcing the brake drum flanges for preventing radial expansion or contraction of the same. As shown, a plurality of outer and inner curved wedge members 33 and 3d, respectively, arev employed for this purpose. The wedge members 33 and 34, which are segments of circular form, are adapted to -be positioned within the circular recess 28. The wedge segments or members 33 engage the outer inclined wall 29 and the outer surface of the brake drum flange or the briquet, as the case may be, and the wedge members34 engage the side of the inclined wall 3| and the ange 2'| or the briquets, as the case may be, as shown in Fig. 2. It will thus be seen that downward pressure on the section |8 will cause the wedgemembers 33 and 34 to exert opposed lateral pressure on the brake iiange and the briquets. The wedge members that contactthe briquets should be coated with'graphite to prevent the briquets from adhering thereto during the sintering operation. The sections of the brazing apparatus-may be built up in like manner, one superposed on the other, to the capacity of the heat treating furnace. Each unit or section has a brake drum attached thereto in the same manner as described above.

When the parts have been assembled'within the furnace, pressure and heat are applied-the heat being substantially that for sintering the briquets, and the pressure being sulcient to cause them to become bonded to the brake drum flange', Usually a pressure somewhere in the neighborhood of 250 pounds per square inch, with a temperature of around 1600" F., will be sulcient, but this will depend upon the nature of the powdered material constituting the briquets.

The brake liners may be attached to either the inner or outer side of the brake drum, as may be required. As shown in the lower section in Fig. 2, the liners 32 are illustrated as being applied 'badly and is not usable.

" -1 `hThe briquets may consistof a single layer of powdered material, as shown at 32a in Fig. 4, or they maybeformed by two or more layers, as

shown in Fig. 5. `Where liners are attached to friction members on brake` drums, the briquets are preferably, though not necessarily, formed of a plurality of layers. In Fig. 5 is shown alhriquet of two-layers 32b and 32. The iniier layer 322er" layer in contact with the brake flange, is preferably of powdered copper because of its heat con-`V ductivity, so that heat generated by the braking operation is conducted away from the friction surface of the liners Vand thereby dissipated.

The brazing apparatus Il may also be used to secure a bimetallic member to a brake drum by a conventional soldering or brazing operation. In other words, in the above description the powdered metal is bonded directly to the flange of the brake drum., It isalso possible to rst sinter and bond the briquet to a thin sheet metal or sheet copper backing member, and to solder or braze the backing member to the flange of the drum. Thus, for example, the pure copper layer 323 of Fig. 5 lmay be substituted by a solid copper member, the briquet being pressed and sintered and bonded to the copper backing in the usual man- If the copper backing member and the flange of the drum are heavily'plated with copper or tin and then assembled in the brazing fixture and heated. the sheet copper backing will be welded or brazed to the flange of the brake drum. However, it is preferred to4 secure thepowdered i metal directly to the flange of the drum The composition of the facing or friction layer may vary for different uses andl installations. The following mixture for the layers 32a and 32b has been found to give satisfactory results:

The briquet must obviously conform to the shape of the flange of the brake drum in which it is to be secured. The only satisfactory manner in which this can be done is to form a ilat rectangular briquet and then bend it to a curvature corresponding to the flange of the drum. Several such arcuate segments are placed end to end to form the complete lining for the flange.

' Due to the danger of fracturing the briquets in curving the same, especiallyin the thicker briquets that may have been sintered, it has been found that if a temporary reinforcing member of thin sheet steel 35 (Fig. 4) be bonded .onto the briquet it may be more easily bent to curvilinear form without fracturing or rupturing the material, and this may be done as disclosed in my Patent No. 2,289,311. This member may be removed or peeled off after thebriquet has been bonded to the brake drum flange 21. This temporary reinforcing member may, if desired, be also used in the multi-layer briquet shown in Fig. 5.

It will thus be seen that the brazing apparatus comprises a plurality of similar units or sections that are superposed or built into a stack that may be increased or decreased in height, depending on the capacity Yof the furnace. observed that suitable pressure may be applied to the stack of sections by the use of the inclined' walls of the grooves in cooperation with the wedge members, and that the brake drums are prevented from'becoming distorted by the heat and pressure applied thereto. K Y

. It is thought from-the foregoing, taken in connection with the accompanying drawings, that the operation and constructionbf my device will be apparent to those skilled in the art', andjhat changes in size, shape, proportion and detailsV may be made without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. In a pressure brazing apparatus, a base section, a plurality of removable sections superposed on the base section forming a stack, .each of said sections being circular in cross-section and having its upper portion stepped, means for detachably connecting a brake drum to each stepped portion except the topmost one with the'brake drum flange extending upwardly above its respective section, each removable section having an upwardly extending V-shape groove in its lower edge extending downward over the adjacent flange, and inner and outer sectional wedge members on opposite sides of each flange for engaging the side faces of said groove for clamping', pressing and bonding a plurality of powdered metal briquets `,against one sideof each angewhen heat and pressure is applied to said stack.

2. In a brazing apparatus for bonding V,powdered metal briquets to brake drum surfaces, an annular member having an annular stepped upper portion on whichl a brake drum having Yan upwardly extending drum flange is adapted to seat, a second annular member having an annular groove extending upwardly from its lower face adapted to seat over said flange, said groove having walls converging upwardly and witnme of said walls inclined to the vertical, and segmental pressure members engaging the walls of said groove for preventing distortion of said flange and for clamping powdered metal briquets to said flange upon heating said apparatus and applying pressure along the axis of said annulary members.

3. In a pressure brazing apparatus for brazing powdered metal briquets to the curved surface of articles comprising a base'section, a plurality of removable sections adapted tov be superposed on said base section to form a stack when assembled, means associated with each section for rigidly holding an article in position such that the curved surface extends axially of the stack, and means associated with each removable section for clamping, pressing and bonding a briquet against the curved surface of n article held by an adjacentr section for bonding the briquets ,to the articles when heat and pressure is applied to said stack.

4. In a pressure brazing apparatus for brazing powdered metal briquets to the ilanges of brake drums, a base section, a plurality of removable sections adapted to be superposed on said base section to form a stack when assembled, means for detachably connecting a brake drum toy one end of each section with the flange extending It will also be 7 toward an adjacent section, and means associated with each removable section for clamping, presst ing and bonding a briquet against the flange of a drum held by an adjacent section for bonding the briquets to the flanges when heat and pressure is applied to said stack.

5. In a device of the class described, an elongated annular member having one end adapted to hold a anged brake drum in position with the flange thereof extending axially outwardly from the member, an annular groove having converging walls disposed in the other end of said member and a plurality of wedge membersadapted to cooperate with said groove to clamp powdered metal briquets against the flange of a brake drum.

SAIVIUEL K. WELLMAN.

REFERENCES CITED The following references are of record in the file' of this patent:

UNITED STATES PATENTS Number Name J Date 1,911,726 Tanner et a1 Mayv 30, 1933 1,967,715 Magruder July 24, 1934 2,035,380 Wilhelm Mar. 24, 1936 2,080,348 Tuitt .May 11, 1937 2,106,904 vWi1he1m, Feb.' 1, 1938 2,114,151 Romig Apr. 12, 1938 2,169,584 Kelley Aug. 15, 1938 2,276,353 Thompson Mar. 17, 1942 2,313,925 Curtin Mar, 16, 1943 Certificate of Correction Patent No. 2,434,237. January 6, 1948. SAMUEL K. WELLMAN It is hereby vcertified that errors appear in the printed specication of the above numbered patent requiring correction as follows: Column 8, line 8, list of references cited, under the heading UNITED STATES PATENTS" beginning with the numeral 1,911,726 strike out all to and including Mar 16, 1943 in line 16, and insert instead the following:

493, 897 Robertson Mar. 21, 1893 1, 608, 715 Barr NOV. 30, 1926 2, O41, 346 Jaques May 19, 1936 2, 086, 41s Babi@ July o, 1937 2, 154, 014 Sinclair Apr. 11,1939 2,169,281 Pfanstiehl Aug. 15, 1939 2,178,527 Wellman Oct. 31, 1939 2,287, 952 Tormyn June 30, 1942 2, 300, 302 Morin Oct. 27, 1942 and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Oflice.

'Signed and sealed this 6th day of April, A. D. 1948.

THOMAS F. MURPHY,

Assistant ommzssz'oner o f Patents.

Certiiicate of Correction Patent No. 2,434,237. January 6, 1948. SAMUEL K. WELLMAN 1t is hereby certiied that errors appear in the printed specication of the above numbered patent requiring correction as follows: Column 8, line 8, list of references cited, under the heading UNITED STATES PATENTS beginning with the numeral 1,911,726 strike out all to and including Mar. 16, 1943 in line 16, and insert instead the following:

493, 897 Robertson Mar. 21, 1893 1, 608, 715 Barr Nov. 30, 1926 2, 041, 346 Jaques May 19, 1936 2, 086, 448 Bai/ie July 6,1937 2,154,014 Sinclair Apr. 11,1939 2, 169, 281 Pfanstiehl Aug. 15, 1939 2, 178, 527 Wellman Oct. 31, 1939 2, 287, 952 Tormyn June 30, 1942 2, 300, 302 Morin Oct. 27, 1942 and that the said Letters Patent should be read With these corrections therein that the same may conform to the record of the case in the Patent Ofce.

Signed and sealed this 6th day of April, A. D. 1948.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

